Organ transplantation and preservation is a field of increasing importance due to the advances in the medical arts and sciences related to organ transplants which have made it possible to transplant a variety of living tissues and organs. It is generally recognized in the art that preservation of living tissue is most effective if the tissue is immersed in a perfusate, nutrient liquid, and is maintained in a refrigerated, hyperbaric environment.
It has been found to be desirable for effective preservation to provide a chamber wherein the temperature is less than 37.degree. C. and the pressure is from two to fifteen bars above ambient atmospheric pressure. Furthermore, it is desirable to perfuse the organ with plasma or other similar fluid which provides the necessary nutrient and oxygen to the organ. This perfusate may also contain additives such as hormones, steroids, penicillin, antibiotics or the like to treat specific conditions found in the organ being preserved. Prior art systems generally provided a hyperbaric chamber for storing the organ under the prescribed environmental conditions and a closed, pressurized reservoir and conduit system as a source of perfusate.
When an organ is being preserved in this manner, the attending physician may require that the perfusate be modified as, for example, to include additives or change the basic composition of the fluid. In the past, the perfusate and the preservation chamber were maintained at equilibrium pressures, either both under hyperbaric conditions or both at ambient pressure. Since it is desirable to provide a hyperbaric environment for the organ, prior preservation systems were closed, pressurized systems, wherein both the perfusate and the preservation chamber were maintained at elevated pressures. In these past systems, it is generally necessary to depressurize the entire system, including the organ preservation chamber, in order to change or modify the perfusate.
It is well known that depressurization of the organ must be done carefully to avoid creating gassy embolisms in the organ tissues. These past systems all suffered from the highly undesirable requirement of having to follow carefully prescribed and time consuming procedures for depressurizing the preservation system each time it was necessary or desired to modify or test the perfusate.